Embodied energy
Embodied energy[1] on Mars is the measure of all the energy required for the preparation of products or services. It allows for a useful comparison of various materials that can be produced in-situ for the construction of martian settlements.
In common materials (from Wikipedia, partially adapted to Mars)
Selected data from the Inventory of Carbon and Energy ('ICE') prepared by the University of Bath (UK)
| Material | Energy MJ per kg | Density kg /m3 | Mars notes | Source |
|---|---|---|---|---|
| Water | 0,5 | 1000 | Melting or condensing from atmosphere | ML |
| Compressed Regolith Blocks (CRB) | 0,5 | 2000 | 5% cement | ML |
| Hydrogen | 180 | Electrolysis of water, 80% efficiency, this also produces large amounts of Oxygen | ML | |
| CO2 | 4 | 1 | Work of compression and liquefaction | ML |
| Propellant (CH4) | 127 | This includes the energy to produce the corresponding Oxygen, atmospheric compression and hydrogen electrolysis. | ML | |
| Food | 1580 | 900-1000 | This also includes biomass, needs to be refined | ML |
| Solar cells[2] | 2088 | Silicon cells, not installed. | ||
| Aggregate | 0.083 | 2240 | This is the energy required to crush and sort the aggregate that is used for concrete production or road building | |
| Concrete (1:1.5:3) | 1.11-2 | 2400 | This is for M20 concrete, slightly better than average concrete | |
| Bricks (common) | 3 | 1700 | ||
| Concrete block (Medium density) | 0.67 | 1450 | ||
| Aerated block | 3.5 | 750 | ||
| Limestone block | 0.85 | 2180 | ||
| Cement mortar (1:3) | 1.33 | Cement with sand mixed in | ||
| Steel (general, av. recycled content) | 20.1 | 7800 | From Iron, does this include iron production? | |
| Stainless steel | 56.7 | 7850 | From Iron ore. Meteoritic iron might require much less energy | |
| Timber (general, excludes sequestration) | 8.5+300 | 480–720 | Unlikely, at first. Bamboo glued structural elements might provide similar services | |
| Glue laminated timber | 12+300 | |||
| Cellulose insulation (loose fill) | 0.94–3.3+300 | 43 | ||
| Glass fibre insulation (glass wool) | 28 | 12 | ||
| Rockwool (slab) | 16.8 | 24 | ||
| Expanded Polystyrene insulation | 88.6 | 15–30 | ||
| Polyurethane insulation (rigid foam) | 101.5 | 30 | ||
| Straw bale | 0.91 | 100–110 | Probably much more expensive on Mars, depends on the value of biomass | |
| Mineral fibre roofing tile | 37 | 1850 | ||
| Clay tile | 6.5 | 1900 | Clay deposits are available | |
| Aluminium (general & incl 33% recycled) | 155-220 | 2700 | Alumina is common, but perhaps not in concentrated ores | |
| Medium-density fibreboard | 11+300 | 680–760 | ||
| Plywood | 15+300 | 540–700 | ||
| Plasterboard | 6.75 | 800 | ||
| Gypsum plaster | 1.8 | 1120 | ||
| Glass | 6-15 | 2500 | ||
| PVC (general) | 77.2 | 1380 | ||
| Vinyl flooring | 65.64 | 1200 | ||
| Terrazzo tiles | 1.4 | 1750 | ||
| Ceramic tiles | 10-12 | 2000 | ||
| Wood | 1200-1500 | 600-800 | Similar to food | ML |
| Wool carpet | 106 | Sheep on Mars? | ||
| Wallpaper | 36.4 | |||
| Vitrified clay pipe (DN 500) | 7.9 | Might be interesting for many uses | ||
| Iron (general) | 25-36 | 7870 | ||
| Copper (average incl. 37% recycled) | 42-140 | 8600 | ||
| Lead (incl 61% recycled) | 25.21 | 11340 | ||
| Ceramic sanitary ware | 29 | |||
| Paint - Water-borne | 59 | |||
| Paint - Solvent-borne | 97 |
Plastics, for example, have a high value of embodied energy and therefore are not the best choices for construction materials, of other choices are available. Note, energy of plastic feedstock may not be included.
Aluminium requires much more energy than Steel or iron and therefore is less likely to be used for construction on Mars.
The values for woods and other biological products in the above table do not include embodied solar energy.
With embodied solar energy:
Food: At an average yield of 3 tonnes per hectare (conservative) embodied energy is about 1580 MJ/kg.
Wood: At 4 tonnes per hectare for bamboo, embodied energy is about 300 MJ/kg. Work to transform it into a usable product should be added from table above.
Embodied energy in solar cells (Wikipedia)
Including cell manufacture, supports and structure. PV cells require very high amounts of energy to manufacture and are likely to be more economical to transport from Earth in the earlier stages of a colony. However, in the long term they produce far more energy than they embody, so solar can be envisioned as a sustainable energy production method for Mars.[2]
| Photovoltaic (PV) Cells Type | Energy MJ per m2 | Carbon kg CO
2 per m2 |
| Monocrystalline (average) | 4750 | 242 |
| Polycrystalline (average) | 4070 | 208 |
| Thin film (average) | 1305 | 67 |
